Protective footgear



April 1966 F. J. LEWIS, JR, ETAL 3,243,898

PROTECTIVE FOOTGEAR 2 Sheets-Sheet 1 Original Filed Dec. 17, 1957 HORIZONTAL BALLISTIC TEST WEDGE FOR ARMORED FOOTWEAR INVENTORf) FREDERICK J. LEWIS JR.

LAWRENCE R. HOLLAND JOHN F. QUINLAN ATTORN Yj April 1966 F. J. LEWIS, JR, ETAL 3,243,898

PROTECTIVE FOOTGEAR Original Filed Dec. 17, 1957 2 Sheets-Sheet 2 ACCOUSTIC FILLER 2B METALYWEDGE FRACTURE LINE/2'7 BALSA PLATFORM E1515 :Eltfizll I fi HORIZONTAL 43 4? INVENTORS 3e 33 FREDERICK J. LEWIS,JR. LAWRENCE R. HOLLAND JOHN F. QUINLAN United States Patent Ofiflce Meme, f iiiiiifi 3,243,89 PROTECTIVE FOOTGEAR Frederick J. Lewis, In, Norfolk, Va., Lawrence R. Holland, Philadelphia, Pa., and John F. Quinlan, Jacksonville, N.C., assignors to the United States of America as represented by the Secretary of the Navy Continuation of application Ser. No. 703,465, Dec. 17, 1957. This application Jan. 4, 1961, Ser. No. 80,695 Claims. (Cl. 36-7.5)

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This application is a continuation of application Serial No. 703,465, filed December 17, 1957 and now abandoncd.

This invention relates to a device for the protection of lower limbs and feet.

Since the introduction of buried charges and booby trapped munitions there has been a need for some method to protect the lower limbs and feet of combatant troops from the blast effect and fragmentation associated wih the detonation of all types of minesparticularly small mines which are easily concealed, inexpensive and can be planted in large numbers by relatively unskilled personnel. In general, a small antipersonnel mine (one containing less than 3 ounces of explosive) will sever or avulse the lower extremities. Whether one or both feet are involved depends on several factors, i.e., the amount of Weight placed on the charge when detonation is effected, the amount and type of charge, the proximity of the feet to the charge, the depth of concealment, etc. Normally, an individual over or very near the exploding charge will lose at least his foot from the ankle down, and more frequently will suffer the loss of an entire leg.

Typical antipersonnel mines tend to rely upon a blast effect rather than on fragmentation for their destructive properties. Applicants have discovered that by placing a deflecting armored wedge between the foot and the exploding charge the force exerted on the foot can be considerably reduced. The wedge has proved considerably more effective than the same thickness of still air between the sole of the shoe and the foot.

An object of the present invention is to tection for the feet and lower limbs.

Another object is to provide a device which will enable troops and mine searching or disposal personnel to traverse mined areas with less difliculty than has formerly been possible.

The advances in orthopedic surgery and treatment can accomplish seemingly impossible feats providing there is actually some bone, muscle and tissue left to work with. Accordingly, it is a further object of this invention to provide a footgear which will prevent severance of the feet and limbs from the blast force of exploding mines.

Still another object of the invention is to provide a protective device which may be incorporated either in a special armored boot or in an attachment for standard field footwear.

Other objects and attendant advantages of the invention will be manifest from a consideration of the following detailed description, claims and drawings in which:

FIG. 1 shows the jet separation effected by an armored wedge when positioned over an exploding antipersonnel mine.

provide pro- FIG. 2 is an isometric View of the wedge of FIG. 1.

FIG. 3 shows an alternative construction of the deflecting wedge.

FIG. 4 shows another alternative of the wedge construction.

FIG. 5 shows the invention associated with an attachment for standard field footgear. In FIG. 5 the toe and heel angle, 43 and 47, hereinafter referred to are clearly evident.

FIG. 6 shows a cut-away isometric view of one form of expendable platform incorporating the deflecting wedge.

FIG. 7 shows another feature of the invention in crosssection in modified form.

FIG. 8 exhibits an alternative form of wedge and expendable platform.

FIG. 9 is a longitudinal elevation showing an unshod human foot fitted onto a footprint wedge.

FIG. 10 is a front elevation of the footprint wedge of FIG. 9.

Referring to the drawings, FIG. 1 shows a wedge 1 which both supports the human foot above the ground and provides a structure for deflecting the force of an exploding mine 7 so as to avoid injury. By the present improvement, a structure has been provided which affords protection without seriously interfering with the walking characteristics of the footgear.

FIG. 2 more fully shows the proportionment of parts and angles of an embodiment which has been used for test purposes. The deflecting angle 6 is the angle between a deflecting face of the wedge 1 and the horizontal. The face angle 5 is here shown as which has been found to b an optimum selection. The illustrated wedge is made of any tough metal such as aluminum, and may be formed in various ways to obtain the desired Wedge. The wedge is placed beneath the foot in a shoe or boot, or as explained hereinafter, an attachment for a standard shoe, with the apex down. The width W approximates four inches in this embodiment which is slightly larger than the Width of the average foot to be protected. The length L of the test wedge also approximates four inches; however, in the finished form of protective footwear this length will approximate that of the wearers boot.

It will be understood that a 70 face angle is practical but not limitative. Assuming a given foot width to be protected, a 4 face angle, for example, has the advantage of raising the foot of the wearer whereas tends to make walking more comfortable. It is preferred but not essential that the face angle not greatly exceed 100 or be less than 45.

FIGS. 3 and 4 illustrate variations of wedge construction, the former consisting of relatively thin metal deflecting faces 2 reinforced by a plastic backing 3, such as fiber glass or Teflon (tetrafluoramethene), and the latter consisting of molded laminated fiber glass 4 with a metal keel insert 9. Either of these variations insures a light durable structure with the desired deflection properties. The converging deflecting faces 2 of the wedge of FIG. 3 and the metal keel insert 9 of FIG. 4 fulfill the requisite of a hard sharp edge proximate to the blast. The laminated fiber glass 4 has excellent armor resistant properties and the illustrated wedges also provide considerable protection from fragmentation injuries. Attention is directed to a feature of the invention shown in FIG. 3 viz., the provision of an acoustic filler 8. The purpose of the filler 8 is to dampen and attenuate any shock transmitted through the wedge. It may obviously be used in any form of wedge which is hollow. Various materials are suitable as filler, for example sound absorbent insulating materials such as Celotex, acoustical, as well as balsa wood or any material similar to those used to make the expendable platform as explained hereinafter.

FIG. illustrates one finished form of the protective footgear. A detachable platform It), formed of a plastic fracturable material in the form of a hull 13, is adapted to be attached to a standard field boot. An armored wedge 12 is enclosed within the platform and extends between a bottom sole 14 and a midsole 15. The midsole is shaped to accommodate the sole of the field boot. An armored toe cap 16 is attached to the forward or toe end of the platform into which the toe of the field boot is inserted. An ankle strap 11 holds the attachment firmly to the boot. The bottom sole 14 is fiat across its width and has suitable curvature in the fore and aft direction to permit normal foot motion in walking. The platform thus allows the benefit of the wedge to be utilized while permitting the wearer the stability advantage of a flat sole, It is obvious that the armored toe cap 16 could be replaced by other fastening means, for example, a pair of clamps such as is common in attaching childrens roller skates to their shoe soles could be used.

In FIG. 6 the wedge is mounted in a hull shaped expendable platform of plastic 13. The platform shown could obviously be used in an attachment as in FIG. 5 or as the sole of a complete special boot.

In FIG. 7 is illustrated a different type expendable platform. The wedge 22 is imbedded in a balsa wood block 21 and filled with acoustic filler 23. Reference has been made hereinbefore to the need for a fracturable platform. A feature of this invention is that the apex of the wedge is resting on and confined by a minimal mass of material. The requirements for optimum protection indicate that the material surrounding the wedge which forms the actual platform for the foot, must blow away and be disintegrated very readily yet be sufliciently rugged to withstand normal abuse in the field. To be certain of effecting the rapid fracture of this material, a preformed fracture line 27, may be engraved or recessed in the lightweight platform material. In operation it may be found advisable to preform several fracture lines. Such a configuration would insure that the jet separation effect would be maximum. The material for the platform can be any material having the following properties: (1) light weight, (2) low sonic propagation velocity, (3) capable of being shattered quickly into very small pieces, (4) relatively soft so as to minimize fragment wounding properties. The acoustic filler 28 should also be light in weight and have a low sonic propagation velocity. Various platform materials have been tried among which are balsa wood, unicellular polyvinylchloride foamed plastics (Ensolite), sound absorbent insulation (Celotex, Acousticel, etc.), polystyrene foams, rubberized hair felt, cork, rubber-resin compounds (Royalite), and resin bonded diatomaceous earth. No particular significant difference has been found between these materials and balsa wood or Ensolite appear to be adequate from the standpoint of ruggedness to withstand field use. It should be pointed out that the plastic hull 13 of FIGS. 5 and 6 is consistent with the above requisites since it would be quite thin and have frangible qualities.

The wedge 32 of FIG. 8 is formed with the upper surface of footprint shape. The material of which it is made may be any of the wedge materials herein before disclosed. It is solid and somewhat simpler and less expensive, due to its approximately vertical fore and aft surfaces 38 and 34, than the refinements illustrated in FIGS. 9 and 10. The expendable platform 33 may be made of balsa wood.

In FIGS. 9 and 10 the upper face of the wedge 42 is shaped to conform to the bottom of the human foot and is slightly larger than footprint dimensions. It will be observed from the drawing that the fore and aft ends of the wedge 48 and 44 are tapered (see also FIG. 5). It is an important feature of this embodiment that the face angle 4-5 (FIG. 10) is constant throughout the length of the wedge and that the same angle or inclination is maintained at the toe and heel. In other words, the toe angle 43, the heel angle 47 and the deflecting angle 46, see FIGS. 9 and 10, are all equal. It may help in visualizing this concept if reference is made to FIG. 2, and it is considered that the deflecting angle 6 is continued around the complete periphery of the wedge instead of only along the deflecting faces as in that embodiment. If the device of FIGS. 9 and 10 is made to maintain this constant angle throughout the peculiar curve of the enlarged footprint configuration, a minimal surface is developed. It will be noted that the vertical height, apex to sole of the Wedge, immediately adjacent the widest part of the foot is higher than in the region of the heel area, in elevation. Again, the peculiarities of the constant angle coupled with the irregular shape of the footprint generate this odd appearing surface. This embodiment represents the minimal weight and therefore surface area available.

It should be understood with any of the embodiments shown, the wedge must be carried up to the outer extremes of the foot in order to realize maximum blast protection for any given face angle of the wedge. It is clear that the wider the foot, the higher the foot will be off the ground when standing on the wedge. As noted herein before the face angle may be considerably varied. At present it does not appear feasible to provide for the raising of the foot any further than six inches for general purpose personnel.

The invention described herein has been successfully tested. It has been found that a substantial diminution of explosive force exerted on the foot can be realized by the use of the footgear described.

The discussion has been primarily directed to the bonefits incidental to the invention where the wearer has had his foot directly over the exploding mine which is the most destructive situation. Tests have been conducted, however, using off-center firing of the mine and it is evident that the invention is even more effective in that case, the projected area seen by the vertical force being less.

The choice of wedge and platform construction utilized is to a great degree dependent on the desired results under the existing conditions. For example, the terrain, climate, condition of the ground (snow, mud, sand, etc.), combat situation, and so on. The manner of fastening the wedge inside the footgear, in itself is not part of the invention and depends on such factors as expense which can be tolerated, etc.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. A protective support for the foot comprising a platform having a midsole and lower sole, said midsole being shaped to fit the foot, and a wedge-shaped deflecting mem her having a flared portion and an apex remote therefrom positioned within said platform with the apex adja cent said lower sole, said apex extending longitudinally of said deflecting member and presenting a sharp edge to said lower sole, said midsole lying within the angle formed by the flared portion of the deflecting member, said deflecting member being formed of material resistant to explosive effects.

2. Protective footgear comprising a fracturable platform having a footprint-shaped midsole and a lower sole,

a deflecting member positioned within said platform and having an upper substantially flat surface supporting said midsole and an apex remote therefrom, said apex being formed by the intersection of two deflecting faces, said deflecting faces defining a face angle therebetween and extending between said apex and-said upper substantially flat surface, said apex extending lengthwise of said member and resting upon said lower sole, said midsole lying within the angle formed by the intersection of said two deflecting faces, said deflecting member being formed of material resistant to explosive effects.

3. The protective footgear of claim 2 wherein said face angle is between 45 and 100 degrees.

4. Protective footgear comprising a fracturable platform having a midsole and a lower sole, a deflecting member positioned within said platform, said deflecting member having an upper surface of footprint shape supporting said midsole and having a wedge shape in transverse cross-section with an apex formed by the convergence of two deflecting faces at said lower sole, each of said faces defining an identical deflecting angle with the horizontal, and in the longitudinal cross-section at remote ends corresponding to toe and heel, two inclined surfaces defining at toe and heel an angle with the horizontal equal to said deflecting angle, said apex defining an edge of minimal surface extending lengthwise of said member in contact with and supported by said lower sole, said midsole lying Within the angle formed by the intersection of said two deflecting faces, said deflecting member being formed of material resistant to explosive effects.

5. A protective platform of predetermined resistance to fracture for supporting objects, said platform comprising an upper surface shaped to fit said objects, a V- angle member supporting said upper surface, said member having a ridge formed by the intersection of its sides, said ridge positioned opposite to said upper surface and extending substantially parallel to the centerline of said surface, said V-angle member being closed at each end, each end tapering from its respective contact with said upper surface to a point on said ridge displaced toward the center thereof, said upper surface lying within the angle formed by the intersection of the sides of said V-angle member, a lower surface positioned substantially parallel to said upper surface, said lower surface having its centerline in the same plane with the centerline of said upper surface, said plane being in substantially perpendicular relation to said upper surface, the midpoints of said centerlines being a line which is p'erpendiclar to said upper surface, said ridge positioned adjacent to the centerline of said lower surface, the lower surface having a periphery substantially identical to the periphery of the upper surface, the periphery of the lower surface disposed such that lines connecting points on the lower surface to corresponding points on the periphery of the upper surface are substantially parallel to said line containing the midpoints of said centerlines, the sides of said V-angle member having a resistance to fracture greater than the resistance to fracture of said objects such that explosive forces originating below said V-angle member are defiected by said sides, a first filler occupying the space between said peripheries and the outer surfaces of said sides, said first filler and said lower surface having a resistance to fracture less than the resistance to fracture of said sides, and a second filler for conditioning concussion, said second filler substantially occupying the space bounded by the inner surfaces of said sides and said upper surface, said V-angle being between 45 and 100, said tapering of said ends being substantially at an angle of 45.

6. A protective platform of predetermined resistance to fracture for supporting objects, said platform comprising an upper surface shaped to fit said objects, a V-angle member supporting said upper surface, said member having a ridge formed by the intersection of its sides,

said ridge positioned opposite to said upper surface and extending substantially parallel to the centerline of said upper surface, said V-angle member being closed at each end, each end tapering from its respective contact with said upper surface to a point on said ridge displaced toward the center thereof, said ridge having its centerline in the same plane with the centerline of said upper surface, said plane being in substantially perpendicular relation to said upper surface, the midpoints of said centerlines being in a line which is perpendicular to said upper surface, said upper surface lying within the angle formed by the intersection of the sides of said V-angle member, the sides of said V-angle member having a resistance to fracture greater than the resistance to fracture of said objects such that explosive forces originating below said V-angle member are deflected by said sides, and a filler for conditioning concussion, said filler substantially occupying the space bounded by the inner surfaces of said sides and said upper surface.

7. Protective gear for a human foot comprising in combination: a platform for supporting the sole of said foot, said platform having an upper surface having a peripheral outline somewhat larger than the outline of said sole, a lower surface and sides extending between said upper and lower surfaces, said upper surface being supported by said sides; a hollow wedge fabricated from material resistant to penetration by high-velocity metallic fragments, said wedge located between said upper and lower surfaces of said platform, the wedge apex lying nearer said bottom surface than the flared sides of said wedge, said upper surface of said platfonm also forming a surface for the opening between the fiared sides of said wedge; and filler material having shock-wave absorbing characteristics, said material lying within the confines of said protective gear.

8. Protective gear for a human foot comprising, in combiation: a platform for supporting the sole of said foot, said platform having an upper surface having a peripheral outline somewhat larger than the outline of said sole, a lower surface and sides extending between said upper and lower surfaces, said upper surface being supported by said sides; a hollow wedge fabricated from material resistant to penetration by high-velocity metallic fragments, said wedge located between said upper and lower surfaces of said platform, the wedge apex lying nearer said bottom surface than the flared sides of said wedge, said upper surface of said platform also forming a surface for the opening between the flared sides of said Wedge; and filler material having shock-wave absorbing characteristics, said material filling the space bounded by said hollow wedge and said upper surface of said platform.

9. Protective gear as set forth in claim 8, wherein said upper surface of said platform is shaped complementarily to the bottom surface of a shoe.

10. Protective gear for a human foot comprising, in combination: a platform for supporting the sole of a shoe covering said foot, said platform having an upper surface having a peripheral outline somewhat larger than the outline of said sole, a lower surface and sides extending between said upper and lower surfaces, said upper surface being supported by said sides; a longitudinal hollow wedge fabricated from material resistant to penetration by highvelocity metallic fragments, said wedge extending longitudinally between said upper and lower surfaces of said platform in the direction of the heel-toe axis of said foot, the wedge apex lying nearer said bottom surface than the flared sides of said wedge, said upper surface of said platform also forming a surface for the opening between .the flared sides of said wedge; and filler material having shock-wave absorbing characteristics, said material filling the space bounded by said hollow wedge and said upper surface of said platform.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Szmyt. Cavicchi. Raven. Sendzimir. Schwab.

8 2,337,165 12/ 1943 Olaszy. 2,405,590 '8/1946 Mason. 2,442,390 6/1948 'Willi-ams 891 :5 JORDAN FRANKLIN, Primary Examiner.

BENJAMIN A. BORCHELT, ARTHUR M. HORTON,

PATRICK D. LAWSON, Assistant Examiners. 

1. A PROTECTIVE SUPPORT FOR THE FOOT COMPRISING A PLATFORM HAVING A MIDSOLE AN LOWER SOLE, SAID MIDSOLE BEING SHAPED TO FIT THE FOOT, AND A WEDGE-SHAPED DEFLECTING MEMBER HAVING A FLARED PORTION AND AN APEX REMOTE THEREFROM POSITIONED WITHIN SAID PLATFORM WITH THE APEX ADJACENT SAID LOWER SOLE, SAID APEX EXTENDING LONGITUDINALLY OF SAID DEFLECTING MEMBER AND PRESENTING A SHARP EDGE TO SAID LOWER SOLE, SAID MIDSOLE LYING WITHIN THE ANGLE FORMED BY THE FLARED PORTION OF THE DEFLECTING MEMBER, SAID DEFLECTING MEMBER BEING FORMED OF MATERIAL RESISTANT TO EXPLOSIVE EFFECTS. 